HVAC systems such as furnaces, air conditioners and the like typically include a heating element and/or a cooling element (collectively referred to herein as “heating/cooling element”); a blower for directing air over the heating/cooling element for subsequent delivery to a building, room, or other area serviced by the HVAC system; and an enclosure for enclosing the heating/cooling element and blower. HVAC systems may also include duct work, various controls, and other components.
It is important that the heating/cooling element of an HVAC system not be operated for too long without concurrent operation of the blower to avoid damage to components of the HVAC system. For example, many newer HVAC enclosures are made of composite plastic materials that may melt or otherwise become damaged if a heating element is operated for too long without operation of the blower. Similarly, the heating element itself may be damaged by excess heat or a cooling element may freeze if the blower isn't operated.
To prevent such damage, HVAC systems typically include control systems that automatically operate their blower motors a short time after the heating/cooling elements are activated (a delay is typically introduced to give the heating/cooling elements time to heat or cool to avoid the blowing of cold air into a room in the winter or hot air in the summer.) Such controls are not effective, however, if the blower motor itself, or the wiring thereto, is damaged, because the blower motor may not turn on even though the control system may call for its operation.
To account for possible blower failure, many HVAC systems include air flow vanes, pressure differential sensors, and the like installed in their enclosures or duct work to sense blower air flow to ensure a minimum air flow over the heating/cooling elements. Unfortunately, these types of air flow sensors are inaccurate, difficult to install, and prone to breakage.
Accordingly, there is a need for an improved way to ensure that a blower motor of an HVAC system is providing sufficient air flow.